[Hardening] F-09: No Email Alerts for Security-Relevant Events.

### The required feature described as a wish

**Description:** CloudStack does not send email notifications to users or administrators when security-relevant events occur on their accounts. Specifically, no alerts are generated for password changes, creation of API keys, failed login attempts, or exposure of data containing secrets, such as `kubeconfig`.

**Affected Components:** Management

**Impact:** Since users have no out-of-band visibility into actions taken on their accounts, an attacker may go undetected indefinitely, establish persistence by creating API keys, try to guess users' passwords, attempt to access users' accounts from an unauthorized source (see F-12), or silently lock the user out by resetting their password. This significantly increases the window of exposure following a credential compromise.

**Steps to Reproduce:**
- Log in to the CloudStack Management UI as any user.
- Change your own password.
- Generate API keys.
- Reveal Kubernetes configuration.
- Attempt to log in with an incorrect password.
- Attempt to log in from an unauthorized source.
- Check for an email notification confirming that any of the above actions occurred.

**Recommended Remediation:** Implement email notifications for security-sensitive account events, including but not limited to the ones listed above. Each notification should include the timestamp, source IP address, and nature of the action performed. All triggering events should additionally be recorded as audit log entries to support forensic investigation and compliance reporting.

未指定原始檔案或測試。先從密碼變更、API-key 建立、登入失敗或未授權登入，以及 Kubernetes 設定暴露的 Management UI 流程開始，接著追蹤其 audit-log 處理與通知路徑。完成的標準是每個列出的安全事件都記錄必要的稽核資料，並傳送一封包含其時間戳記、source IP 和動作的電子郵件。

由索引模型根據 Issue 內容生成。